Celebrity chef Nigella Lawson and her daughter were “so off (their) heads on drugs” that she let her assistants go on a $500,000 shopping binge, her ex-husband told a London court.

Advertising executive Charles Saatchi was testifying at the preliminary phase of the fraud trial of sisters Francesca and Elisabetta Grillo.

But the bombshell of the day was Saatchi’s email to his ex-wife — the pair split after he allegedly attacked her at a London café — read by Judge Robin Johnson.

PHOTO: Sunday PeopleThe cover of Sunday People that shows Nigella Lawson allegedly being choked by the hands of husband Charles Saatchi while at lunch in a London restaurant on June 9, 2013.

“Of course now the Grillos will get off on the basis that you (and) Mimi (Lawson’s daughter) were so off your heads on drugs that you allowed the sisters to spend whatever they liked and yes I believe every word they have said,” the email says.

Detectives asked Saatchi what exactly he meant in the message to Lawson.

Saatchi told police: “At the time of sending the email I was completely astounded by the scale of drug use set out in the statements (from the defendants).

“Nevertheless I did believe the allegations that I’m referring to in the email. I have been asked whether it referred to a belief that Nigella or the children permitted the sisters to spend whatever they liked.

“I can’t remember precisely what I had in mind. On reflection, I was simply speculating that the sisters would use this information to defend themselves.”

Saatchi said he was oblivious to any drug use by Lawson during their 10-year marriage and that it came to light only after the pair split — and that the café argument was triggered by her use of drugs.

The Grillo sisters’ lawyers describe them as “innocent pawns” in a bitter public relations war between Saatchi and Lawson.

Lawson is expected to give evidence during the two-week trial.

—

CORRECTION: This story has been updated to make a small change in the first paragraph (from “her” to “(their)” and fix an error in the paragraph starting “Lawson, 53…”